Recognize common diseases in freshwater fish as well as some disease prevention measures and aquatic medicine products to treat diseases, contributing to minimizing damage caused by epidemics.
In aquaculture environment, there are many diseases that can affect the health and development of fish, causing great damage to farmers.
1. ANCHOR WORM DISEASE
Anchor Worm Disease is a common disease in freshwater and brackish water fish.
– Cause: by anchor parasites, which live on the body of fish, especially grass carp, silver carp and tilapia. This is a crustacean parasite that can attach to the body of fish, causing serious damage to farmed fish.
– Symptom
+ Ulcers often appear on the skin, gills and fins due to the anchor worm’s hooks penetrating deep into the fish tissue.
+ Fish become weak and lethargic due to loss of energy. Parasites suck nutrients from the fish, making them weak and susceptible to other secondary diseases.
+ Sometimes anchor worms can be seen with the naked eye. They may appear as long white strands, like pieces of thread, protruding from the fish’s body.
+ Infected fish may reduce or stop eating, causing rapid deterioration of the body.
Image of fish farming
– Prevention and treatment
+ Treatment using antiparasitic drugs
+ Maintain good water quality (temperature, pH, dissolved oxygen) and ensure effective filtration to minimize anchor worm breeding grounds.
+ Disinfect fish tanks and equipment regularly with disinfectants such as formalin and potassium permanganate to prevent parasite growth.
+ Supplementing complete nutrition, minerals and vitamins for fish helps strengthen the natural immune system.
Anchor worm disease, if not detected and treated promptly, can cause high mortality in fish and spread rapidly in the aquarium. Therefore, it is necessary to focus on prevention and clean environmental management to minimize the risk of infection.
2. SAPROLEGNIA FUNGUS
Saprolegnia Fungus commonly found in fish and fish eggs, and can cause serious damage if not detected and treated promptly.
– Causes of disease
+ Poor water quality: Polluted water, high in organic matter, rarely changed water.
+ Injured Fish: Wounds or lesions on the skin, gills or fins of fish allow fungi to enter.
+ Fish with weakened immune systems: Fish that are stressed, malnourished, or weakened by other diseases are also more susceptible to fungal infections.
– Symptoms of the disease
+ White or gray cotton-like fungal patches appear on the skin, fins, gills or around the eyes of the fish. This is the most typical sign of ich.
+ Ulcers on fish skin: Fungi often cling to open wounds or damaged skin areas.
+ Fish stop eating, swim lethargically and may separate from the school, due to the discomfort caused by the fungus.
+ Fish eggs infected with fungus: Fish eggs can be attacked by fungus, causing the eggs to turn opaque and not hatch.
– Prevention and treatment
+ Maintaining good water quality requires controlling water quality (pH, dissolved oxygen, temperature) and changing water regularly.
+ When detecting signs of injury in fish, immediate treatment is needed to prevent fungus from attacking damaged skin areas.
+ A proper diet helps fish strengthen their immune system and resistance, reducing the risk of infection.
+ Disinfect the tank and equipment: Make sure the fish farming equipment is clean and disinfected with an antiseptic or salt solution to remove fungal spores.
+ Use antifungal medications
Saprolegnia Fungus is a common and contagious problem in aquaculture. Prevention and early detection of fungal diseases are very important to avoid major losses. Always maintain a good living environment for fish and monitor fish health regularly for timely detection and treatment.
3. ICHTHYOPHTHIRIUS MULTIFILIIS
Cause: Parasites are the main culprit. This is a type of single-celled organism that can attack and parasitize the skin, gills and fins of fish. The disease often breaks out when the water environment is not good, the fish is stressed, or there is a sudden change in temperature.
Symptoms of the disease
– Small white spots (0.5 – 1 mm) appear on the skin, gills, and fins of the fish. These white spots are about the size of grains of sand.
– Swimming sluggishly, often floating on the surface or congregating near areas of high oxygen (aerators).
– Fish lose their appetite and can rapidly deteriorate if left untreated.
– The fish’s gills may turn brown or red, and the fish may breathe rapidly due to parasite damage to the respiratory organs.
Image of fish farming
Treatment and prevention
– Increase water temperature: Typically, increasing the water temperature to around 28-30°C for a few days will do the trick.
– Change the water regularly and maintain good water quality: This helps remove free-ranging larvae and reduces the chance of spreading disease.
– Maintain stable water quality (pH, temperature, oxygen).
– Control the living environment to avoid stress for fish by not putting too many fish in one tank and providing enough space and clean environment.
Ichthyophthirius multifiliis caused by melon worm, if not treated promptly, can cause death to fish in a short time. Therefore, it is necessary to detect and handle it quickly when the initial symptoms are seen.
4. THELOHANELLUS KITAUEI
A disease related to the digestive system, in which fish develop cysts or fluid-filled sacs in the intestinal wall.
Causes of disease
– Improper diet: One of the main causes of intestinal cysts is an unbalanced diet, especially when fish are fed too much dry food or food that is not well digested.
– Poor feed quality: Feed containing too much insoluble fiber or difficult to digest ingredients can cause blockages and cyst formation in the fish’s intestinal tract.
– Genetics or weak constitution: Some individuals may be susceptible to this disease due to genetic factors or poor resistance of the digestive system.
Symptoms of the disease
– Swollen belly: Fish with intestinal cysts often have a distended belly due to fluid accumulation in the cyst.
– Constipation or poor digestion: Fish may have difficulty digesting food, showing signs of constipation, no excretion or abnormal stools.
– Decreased appetite: Sick fish may stop eating or eat very little due to abdominal discomfort.
– Lethargic swimming: Fish may swim sluggishly or float on the surface of the water due to a swollen belly.
– Body Deformity: If the disease persists, the fish may experience body deformities, and the size of the cyst may alter the overall shape of the fish.
Prevention and treatment
– Provide nutritious and easily digestible feed, avoid overfeeding dry feed or feed with high insoluble fiber content. Use quality feed and avoid using poor quality or expired feed.
– Good water management: Maintain a clean living environment with stable water quality. Regularly change water and control parameters such as pH, temperature, and dissolved oxygen.
– Avoid stress for fish: Stress is one of the factors that weaken the immune system of fish, making them susceptible to disease. Ensure a comfortable living space and avoid factors that cause stress for fish.
– Regularly monitor fish health: Check fish regularly to detect unusual symptoms early and take timely measures.
– Use of drugs to treat intestinal inflammation: If the cyst is caused by bacterial or parasitic infection, antibiotics (as prescribed by your veterinarian) can be used to reduce inflammation and kill pathogens.
Thelohanellus kitauei in fish are not common but can have serious consequences if not treated promptly. Dietary management, environmental management and regular health monitoring of fish are important for prevention and early detection of this disease.
Image of fish farming
5. BRANCHIOMYCES
A serious disease in fish. This disease directly affects the fish’s gills, causing gill tissue necrosis, reducing respiratory capacity and leading to death if not detected and treated promptly.
Causes of disease
– Branchiomyces fungi often appear in poor quality, polluted water environments, containing a lot of organic matter and lacking oxygen.
– This fungus thrives in high water temperatures, especially in summer or in tanks with high fish density and infrequent water changes.
Symptoms of the disease
– Gill tissue necrosis: This is the main symptom. The fish’s gills are damaged, turning brown, red or black, with obvious necrotic patches.
– Difficulty breathing: Due to the fungus destroying gill tissue, fish have difficulty exchanging gases, which is manifested by rapid breathing, opening their mouths and swimming to the surface of the water to find oxygen.
Prevention and treatment
– Always maintain a clean, oxygen-rich, pH-balanced water environment. Minimize excess organic matter and other waste to prevent fungal growth.
– Reduce stocking density: Keeping fish at the right density will help reduce stress on fish and prevent the spread of disease.
– Water temperature management: Avoid water temperature being too high for a long time. If possible, keep the water temperature stable, avoid overheating which causes stress to the fish.
– Improve fish health: Provide adequate nutrition and supplement vitamins and minerals to strengthen the fish’s natural immune system, helping them fight infections.
– Use of antifungal drugs: must be used at recommended dosage to avoid harming fish.
Branchiomyces is a serious disease in fish, especially in high density farming conditions and substandard water conditions. Water quality management and early detection of disease symptoms are important for prevention and control of this disease.
Through the above information, farmers will better understand the 5 common diseases in fish, as well as the causes, symptoms, and effective prevention and treatment methods for each type of disease.